Electrolytic production of allyl alcohol



Patented Feb. 22, 1949 ELECTROLYTIC PRODUCTION OF ALLYL ALCOHOL Joseph E. Bludworth, Max 0. Robeson, and Harry A. Truby, Jr., Corpus Christi, Tex., assignors to Celan'ese Corporation of America, a corporation of Delaware v .No Drawing. Application April 12, 1945,

Serial'No. 588,076

This invention relates to the production of organic compounds, and relates 'm ore' particularly to the production of unsaturated aliphatic alcohols by processes involving the electrolytic reduction of unsaturatedaliphatic aldehydes. An object of this invention is to provide an 'eflicient and economical process for the reduction of unsaturated aliphatic aldehydes to the corresponding unsaturated aliphatic alcohol.

Anotherobjectof this invention is the production of allyl'alcohol by the electrolytic reduction of acrolein.

Other objects of this invention will appear from the following detailed description.

Unsaturated aliphatic aldehydes, such as acrolein, constitute a by-product of oxidation reactions involving the vapor phase oxidation of aliphatic hydrocarbons with air or oxygen at elevated temperatures. These unsaturated aldehydes do not have any extensive commercial applications and their conversion in an eflicient and economical manner to compounds possessing wider commercial utility would increase the general efiiciency and value of such oxidation processes.

We have now discovered that unsaturated aliphatic alcohols may be obtained from the corresponding unsaturated aliphatic aldehydes by a direct process involving the electrolytic reduction of the carbonyl group of said unsaturated aliphatic aldehyde employing an electrolytic cell provided with a suitable cathode and containing an electrolyte adapted to effect the desired carbonyl reduction. Thus, in accordance with the novel process of our invention, acrolein may be directly reduced to allyl alcohol by electrolytic reduction operations wherein acrolein is added in a batch or step-wise manner to the gas-tight cathode chamber of an electrolytic cell having a copper, lead, mercury-plated lead or zinc cathode and containing a dilute, aqueous solution of sulfuric acid as the electrolyte, and then a direct current is passed through the cell. Preferably, the solution of electrolyte also contains added agents, such as, for example, ferrous sulfate and zinc acetate, which act to inhibit the addition of hydrogen to the double bond yet enhance the reduction of the carbonyl group. The allyl alcohol produced may be separated from the electrolyte as well as from certain by-products of the reaction, which may be formed in the cathode chamber, in a satisfactory degree of purity.

The direct current employed for the electrolytic reduction may be at a voltage of up to volts, and is preferably 2 to 4 volts. The am- 4 Claims. (01. 204-77) perag-e employed depends, of course, upon-"the cathode area and may vary considerably. The' amperage should be suflicient, employing a cathode of a given areajto yield a cathodic current density preferably of from about 1 to'2 amperes per square decimeter during the reduction process. The cathodic current density may, however, be as high as 5 amperes per square decimeter or as 'low as 0.5 ampere per' square decimeter.

During reduction the electrolyte in the cathode chamber is preferably maintained at a tempera ture of to F. and electrolysis is continued for 2 to 20 hours until the current passed through the cell has delivered at least that chemically equivalent current, as measured in coulombs, theoretically necessary to effect the desired re ducticn of theacrolein to allyl alcohol. D While the use of sulfuric acid "as the electro'-'- lyte is preferred, other electrolytes such as sodium bicarbonate, sodium bisulfate or magnesium sulfate may be employed. The sulfuric acid electrolyte is usually employed in the form of an aqueous solution of a concentration of 1 to 40%, and preferably of about 5%, by weight. The added agents such as ferrous sulfate and zinc acetate may be present in the electrolyte in concentrations of 0.1 to 1.0% by weight. Hydroquinone which acts as a polymerization inhibitor may also be present in the electrolyte in concentrations of 0.1 to 1.0% by weight.

As stated, the cathode may be formed of copper, lead, mercury-plated lead or zinc while the anode may be of any suitable conducting metal or other material such as graphite. The cathode may comprise the outer wall of the electrolytic cell. The cathode chamber in which the reduction takes place is preferably formed by placing a porous diaphragm of, for example, Alundum, between the cathode and the anode to form the desired, separated cathode and anode chambers. I

In order further to illustrate our invention, the following example is given:

Example 25 parts by weight of acrolein are entered into the cathode chamber of an electrolytic cell provided with a mercury-plated lead cathode and containing 825 parts by weight of an aqueous 5% solution of sulfuric acid to which has been added 2 parts by weight of ferrous sulfate, 2 parts by weight of zinc acetate and 2 parts by weight of hydroquinone. The anode chamber contains 200 parts by weight of 5% aqueous sulfuric acid. A direct current of 5.2 amperes at a 3 voltage of 3.2 volts is passed through the cell for five hours with the temperature of the cell at 77 F. The cathode area is such that the current density is 1.28 amperes per square decimeter. At the completion of thereduction reaction eng. when the chemically equivalent amount of current necessary to effect the reduction has been passed through the cell; the unreacted acrolein is re-;

moved by distillation. The allyl alcohol is formed in a yield of 50%. I

Our reduction process is a relatively simple modev of obtaining allyl alcohol-tdirectly f rom acrolein, and in a satisfactory degree of purity. The allyl alcohol obtained'may-be employedfor esterification with any desired acid, or in other reactions adapted to yield valuable organic compounds. J

It is to be understood that the foregoing detailed description is given merely by wayof illustration and that many :variations may be made therein without departing from the spirit of'our invention.

*fHaving described our invention what we desire to secure by Letters Patent is:

.1. Process for ,the production of allyl alcohol, which comprises subjecting acrolein to the cathodic reducing action of a direct electric current in a mediumcomprising a 1 to 40% by weight aqueoussolution of sulfuric acid containing 0.1 to

1% -by-weighttof ferrous sulfate and 0.1 to 1% by weighhof zinc acetate while maintaining a cathodic current density of 0.5 to 5.0- amperes per square decimeter and an electrolyte temperature of 60 t9,10,0\F.

.2. .Process for the production of allyl alcohol,

which comprisessubjecting acrolein to the cathodic reducing action of a direct electric current in-a medium comprising a 1 to 40% by weight solution of sulfuric acid containing from 0.1 to 1.0% by'weight of ferrous sulfate and 0.1 to 1% byweight of zinc .acetate while maintaining a cathodic currentrdensity of 0.5 to 5.0 amperes per square decimeter and an electrolyte tempera- Process for the production of allyl alcohol,

1 which comprises subjecting acrolein to the cathodic reducing action of a direct electric current in a medium comprising a 5% by weight aqueous solution of sulphuric acid containin from 0,1;to 1.0% by weight of hydroquinone, 0.1 to 1% by weight. of ferrous sulfate and 0.1 to 1% byweight of zinc acetate while maintaining a cathodic cur.- rent density of 0.5 to 5.0 amperes per square decimeter and an electrolyte-temperature of 60 to 100F.

JOSEPH E; BLUDWORTH.

MAX 0. ROBESON.

HARRYAJIRUBY, JR.

REFERENCES CITED The following references are of record in the file of this patent:

Read et al., Journal of the American Chemical Society, vol. 48, pp. 14014405 (1926). 

